Spray formed thin layers having fine features

ABSTRACT

According to one embodiment, a composite mold for use in molding a part having a textured surface is disclosed. The composite mold includes a mold base that forms the base of the composite mold. The mold base includes a mold base surface. The composite mold also includes a spray formed thin layer including a first surface having one or more fine features and a second surface opposing the first surface. The second surface is coupled to the mold base to form the composite mold having the first surface as the molding surface. The composite mold is capable of forming a molded part having a textured surface including surface features representing a reciprocal facsimile of the one or more fine features on the molding surface.

BACKGROUND OF THE INVENTION

1. Technical Field

One aspect of the present invention relates to spray formed thin layers having fine features.

2. Background Art

Many plastic parts in vehicle interiors are formed using molding processes, such as injection molding or thermoforming. A typical injection molding process includes filling a mold cavity having a molding surface with a thermoplastic plastic melt under relatively high pressure to form a part within the mold cavity, opening the mold after the part has cured, and removing the cured part from the mold. A typical thermoforming process includes extruding a plastic sheet, placing the plastic sheet on a mold such that the plastic sheet contacts a molding surface, and drawing the plastic sheet into the shape of the mold surface by heat and/or negative force, e.g., a vacuum.

Some interior plastic parts on vehicles include exposed surfaces. Non-limiting examples include door panels, door trim, dashboards, center consoles, glove compartment doors, and seat trim. Vehicle customers expect the exposed surfaces of these plastic parts to have a textured quality. However, plastic parts formed by injection molding, thermoforming, and other molding processes may have a smooth and/or shiny surface, thereby requiring post-processing steps to impart a textured quality to the molded plastic surface. The post-processing steps may include the use of additional tooling and resources, which may be costly and time consuming.

In light of the foregoing, what is needed is a process of forming thin layers having fine features for use as molding surfaces in molding processes, such as injection molding or thermoforming processes. What is also needed is a method for forming plastic articles having fine features from spray formed thin layers having fine features.

SUMMARY

According to one embodiment, a composite mold for use in molding a part having a textured surface is disclosed. The composite mold includes a mold base that forms the base of the composite mold. The mold base includes a mold base surface. The composite mold also includes a spray formed thin layer including a first surface having one or more fine features and a second surface opposing the first surface. The second surface is coupled to the mold base to form the composite mold having the first surface as the molding surface. The composite mold is capable of forming a molded part having a textured surface including surface features representing a reciprocal facsimile of the one or more fine features on the molding surface.

The one or more fine features can include one or more grooves and one or more projections. The grooves and/or projections can include an arcuate portion and/or linear portion. In at least one embodiment, the spray formed thin layer is formed of a metal or metal alloy. The spray formed thin layer can have a nominal thickness of 2 to 20 mils.

The composite mold can further include an adhesive for adhering the second surface to the mold base. The mold base is formed of a metal or metal alloy. In at least one embodiment, the molded part is a part for the interior of a vehicle.

The one or more fine features can include one or more grooves and one or more projections. The grooves and/or projections can include an arcuate portion and/or linear portion. In at least one embodiment, the spray formed thin layer is formed of a metal or metal alloy. The spray formed thin layer can have a nominal thickness of 2 to 20 mils. The spray formed thin layer can be formed of a metal or metal alloy having a metal oxide content of less than or equal to 5%. The one or more fine features can be an intricate array of channels.

According to another embodiment, a spray formed thin layer is disclosed. The spray formed thin layer includes a first surface and a second surface opposing the first surface, and a layer portion extending between the first and second surfaces. The first surface includes one or more fine features.

According to yet another embodiment of the present invention, a method for forming a spray formed thin layer is disclosed. The method includes providing a spray target having a spray surface; depositing a metal spray onto the spray target surface to form a deposit layer having an interfacing surface; and releasing the deposit layer from the spray target surface.

The providing step can include forming one or more fine features on the interfacing surface. In at least one embodiment, the depositing step includes forming one or more fine features on the interfacing surface.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of an apparatus for forming a deposit layer on a spray target, depicted in cross-section, according to at least one embodiment of the present invention;

FIG. 1 a is a cross-sectional, fragmented, side view of a deposit layer having geometric features and a spray target according to at least one embodiment of the present invention;

FIG. 1 b is a cross-sectional, fragmented, side view of a deposit layer having geometric features according to at least one embodiment of the present invention;

FIG. 1 c is a cross-sectional, fragmented, side view of a deposit layer and a mold base according to at least one embodiment of the present invention;

FIG. 1 d is a cross-sectional, fragmented, side view of a deposit layer and a mold base according to at least one embodiment of the present invention;

FIG. 1 e is a cross-sectional, fragmented, side view of a mold and a molding material according to at least one embodiment of the present invention;

FIG. 1 f is a cross-sectional, fragmented, side view of a mold and a molding material according to at least one embodiment of the present invention;

FIG. 2 is a flowchart depicting the method steps for forming a deposit layer according to at least one embodiment of the present invention;

FIG. 3 is a flowchart depicting the method steps for molding a part using a deposit layer according to at least one embodiment of the present invention;

FIG. 4 is a perspective view of an interior vehicle surface having a textured surface according to at least one embodiment of the present invention;

FIG. 5 is a flowchart describing the steps of forming a bipolar plate from a first and second deposit layer according to an embodiment of the present invention; and

FIGS. 6 a and 6 b depict a bipolar plate formed using the process steps set forth in FIG. 5.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE PRESENT INVENTION

Except where expressly indicated, all numerical quantities in this description indicating amounts of material or conditions of reaction and/or use are to be understood as modified by the word “about” in describing the broadest scope of the present invention. Practice within the numerical limits stated is generally preferred.

The description of a single material, compound or constituent or a group or class of materials, compounds or constituents as suitable for a given purpose in connection with the present invention implies that mixtures of any two or more single materials, compounds or constituents and/or groups or classes of materials, compounds or constituents are also suitable. Also, unless expressly stated to the contrary, percent, “parts of,” and ratio values are by weight. Description of constituents in chemical terms refers to the constituents at the time of addition to any combination specified in the description, and does not necessarily preclude chemical interactions among constituents of the mixture once mixed. The first definition of an acronym or other abbreviation applies to all subsequent uses herein of the same abbreviation and applies mutatis mutandis to normal grammatical variations of the initially defined abbreviation. Unless expressly stated to the contrary, measurement of a property is determined by the same technique as previously or later referenced for the same property.

FIG. 1 depicts a side view of an apparatus 10 for forming a deposit layer 12, depicted in cross-section, according to at least one embodiment of the present invention. FIG. 2 is a flowchart 60 depicting the method steps for forming the deposit layer 12 according to at least one embodiment of the present invention. FIGS. 1 and 2 are considered concurrently as follows.

The method, as outlined in flowchart 60 of FIG. 2, includes the step of depositing a metal spray 14 onto a spray target surface 16 of a target 18. The depositing step can be accomplished by a spray forming process, and in certain embodiments, a cold arc thermal spraying (CASP) process. U.S. patent application Ser. No. 11/162,508, which has a filing date of Sep. 13, 2005 and is entitled “Method for producing a variable flow of melted material and articles therefrom,” discloses a CASP process that is suitable for use with one or more embodiments of the present invention, and is hereby incorporated by reference. On Mar. 15, 2007, this application published as U.S. Pat. Pub. No. 2007/0056933.

In block 62 of FIG. 2, the spray target surface 16 of the target 18 is provided. In at least one embodiment, the target 18 can be a substrate formed of a monolithic material or formed of various components. In at least one embodiment, the target 18 can be made of a material that is susceptible to heat damage. In such embodiments, the CASP method can be utilized as a relatively low temperature spraying process that presents a low risk of damaging the heat susceptible substrate. Non-limiting examples of substrate materials that may be susceptible to heat damage include epoxy materials, silicone materials, polymer foams, fiberboards, fiber laminates, plastics, laser-light-cured resins, laminated paper, wax, wood, and sintered ceramics.

In block 64 of FIG. 2, the metal spray 14 is deposited onto the spray target surface 16 to form the spray deposit 12. The metal spray 14 can be emitted from a spray gun or other suitable device, such as thermal spraying devices, plasma spray devices, HVOF thermal spraying devices, and atomized metal spray devices. In at least one embodiment, the metal deposit 12 has a nominal thickness of 2 to 50 mils, and in other embodiments, the nominal thickness is 2 to 20 mils, and in yet other embodiments, the nominal thickness is 2 to 10 mils. In at least one embodiment, the metal spray 14 is comprised of a corrosion resistant metal or metal alloy, for example, stainless steel, titanium, chromium, nickel and alloys thereof.

As shown in FIGS. 1, 1 a and 1 b, the spray target surface 16 includes one or more geometric features 20, which can impart one or more complimentary geometric features 22 on the back surface 24 of the deposit layer 12 and/or can impart one or more reciprocal geometric features 26 on the front surface 28, i.e., the surface substantially contacting the spray target surface 16 during the spray forming step.

The one or more geometric features 20 can include fine surface features, such as grooves and/or projections having linear and/or curved portions. In at least one embodiment, the one or more geometric features 20 include a complex matrix of grooves and projections that can impart a textured surface upon the back surface 24 and/or front surface 28. The textured surface can give an appearance of leather graining and/or a weaving pattern based on the one or more geometric features 20.

In at least one embodiment, the aspect ratio (width to depth ratio) of the grooves included in the one or more geometric surfaces 20 is greater than 1. In at least one embodiment, the grooves can have a depth from the nominal surface 30 of the spray target 18 in the range of 0.1 to 20 mils, and in other embodiments the grooves can have a depth is in the range of 10 to 20 mils, and in yet other embodiments, the depth is in the range of 0.1 to 5 mils. In at least one embodiment, the grooves can have a width (or rough diameter) in the range of 0.1 to 40 mils, and in other embodiments, the grooves can have a width (or rough diameter) in the range of 20 to 40 mils, and in yet other embodiments, the width is in the range of 0.1 to 5 mils.

In at least one embodiment, the projections included in the one or more geometric surfaces 20 can have a height from the nominal surface 30 in the range of 0 to 2 millimeters, and in other embodiments, the projections can have a height form the nominal surface 30 in the range of 1 to 2 millimeters. In at least one embodiment, the projections can have a width (or rough diameter) in the range of 0 to 2 millimeters, and in other embodiments, the projections can have a width (or rough diameter) in the range of 1 to 2 millimeters.

In block 66, the deposit layer 12 is released from the target 18. In at least one embodiment, before the depositing step 64, the spray target surface 16 can be at least partially coated with a material for promoting adhesion of the metal spray 14 and/or subsequent release (step 66) of the spray deposit 12. Non-limiting examples of such materials include water-soluble materials and/or materials that degrade with heat. Specific non-limiting examples include polyvinyl alcohol, epoxies, and silicates.

Turning to FIG. 3, a flowchart 100 depicts the steps of using the deposit layer 12 to mold a part with a textured surface. In block 102, a deposit layer is coupled to a mold base to form a mold. Non-limiting examples of materials that can be utilized for the mold base, include, but are not limited to steel, aluminum, zinc alloy, epoxy, and epoxy metal composites. The mold may be used in any suitable molding process, for example, injection molding or thermoforming.

As depicted in FIG. 1 c, the deposit layer 12 is coupled to a mold base 36 such that the front surface 28 of the deposit layer 12 interfaces with the surface 38 of mold base 36. The coupling of the deposit layer 12 and the mold base 36 forms a composite mold 40. The deposit layer 12 can be coupled to the mold base 36 through any suitable means, for example, mechanical connection or chemical adhesion. In FIG. 1 c, the back surface 24 of the deposit layer 12 is facing away from the mold base 36 such that the back surface 24 forms the molding surface for the composite mold 40. The molding surface includes the one or more geometric feature 22 on the back surface 24.

As depicted in FIG. 1 d, the deposit layer 12 is coupled to the mold base 36 such that the back surface 24 of the deposit layer 12 interfaces with the surface of mold base 36. The coupling of the deposit layer 12 and the mold base 36 forms a composite mold 42. The deposit layer 12 can be coupled to the mold base 36 through any suitable means, for example, mechanical connection or chemical adhesion. In FIG. 1 d, the front surface 28 of the deposit layer 12 is facing away from the mold base 36 such that the front surface 28 forms the molding surface for the composite mold 42. The molding surface includes the one or more geometric features 26 on the front surface 28.

In block 104 of flowchart 100, a part can be molded with a textured surface using a composite mold, for example composite mold 42. As shown in FIG. 1 e, a molding material 44 is shown as conforming to the molding surface 46. In at least one embodiment, the molding material is a thermosetting plastic, although other suitable materials for molding processes are contemplated by the present invention. According to one embodiment of the present invention, this conformance is achieved using a thermoforming process, wherein the molding material 44 is drawn into the shape of the mold surface 46 by heat and/or negative force, e.g., a vacuum. The interfacing surface 48 of the molding material includes a reciprocal facsimile of the shape of front surface 28, including a reciprocal facsimile of the one or more geometric features 26. After the drawing step, the molding material 44 is released from the composite mold to obtain a molded part.

In at least one embodiment, the nominal thickness of the molded part is in the range of 1 to 250 mils. In other embodiments, the nominal thickness of the molded part is in the range of 1 to 100 mils.

As shown in FIG. 1 f, the composite mold 42 is utilized in an injection molding process. A molding material 50 is injected into a molding cavity 52 through aperture 54 by an injector pin 56, using a conventional injection molding process and materials. The interfacing surface 48 of the molding material includes a reciprocal facsimile of the shape of front surface 28, including a reciprocal facsimile of the one or more geometric features 26. After the injection molding process is completed, the molding material 44 is released from the composite mold to obtain a molded part.

In at least one embodiment of the present invention, the molded part can be utilized as a vehicle part, for example, vehicle interior parts. Non-limiting examples of vehicle interior parts include door panels, door trim, dashboards, center consoles, glove compartment doors, and seat trim. FIG. 4 is a perspective view of a seat trim surface having a textured surface that can be produced by one or more methods of the present invention.

In another embodiment of the present invention, the deposit layer 12 can be utilized as at least one component of a vehicle part. For example, the deposit layer 12 can be utilized as a fuel cell bipolar plate. FIGS. 5, 6 a and 6 b depict one method of forming a bipolar plate from a pair of deposit layers. Turning to FIG. 5, a flowchart 150 is depicted for forming a bipolar plate according to one embodiment of the present invention. In block 152, a first deposit layer 200 is formed by a spray forming process, such as the process depicted in FIG. 2. The front surface 202, i.e., the surface contacting the spray target surface during spray forming, contains detailed and intricate gas flow channels whereas the rear surface 204, i.e., the surface opposing the front surface, includes an inverted facsimile of the gas flow channels on the front surface 202. However, the rear surface 204 has a rougher surface texture than the front surface 202.

In block 154, a spray forming process or other suitable process forms a second metal layer 206. The front surface 208 contains detailed and intricate gas flow channels substantially similar to the channels contained on front surface 202. The rear surface 210 includes an inverted facsimile of the gas flow channels on the front surface 208 substantially similar to the inverted facsimile contained on rear surface 204. Again, the rear surface 210 has a rougher surface texture than the front surface 208.

In block 156, the bipolar plate 212 is formed by matching the inverted facsimile of rear surface 204 with the inverted facsimile of rear surface 210, as depicted by the arrows 214 of FIG. 5 a. Subsequently, deposit layers 200 and 206 are bonded to one another to form a coolant passageway 216 therebetween.

The resulting bipolar plate 218 includes front surfaces 202 and 208, each containing an intricate array of channels for distributing fuel and oxidant gases to a membrane electrode assembly (MEA). The bipolar plate 218 also includes a coolant passageway 216 bounded by rear surfaces 204 and 210, each containing a relatively rough surface texture to enhance heat transfer between the coolant and the fuel cell stack.

In at least one embodiment, the bipolar plates formed by the CASP process have a relatively low oxide content, which may offer improved electrical and thermal conductivity relative to bipolar plates formed using conventional methods. In at least one embodiment, the oxide content is in the range of 2-5%.

As required, detailed embodiments of the present invention are disclosed herein. However, it is to be understood that the disclosed embodiments are merely exemplary of an invention that may be embodied in various and alternative forms. While embodiments of the have been illustrated and described, it is not intended that these embodiments illustrate and describe all possible forms of the invention. Rather, the words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the invention.

In accordance with the provisions of the patent statute, the principle and mode of operation of this invention have been explained and illustrated in its various embodiments. However, it must be understood that this invention may be practiced otherwise than as specifically explained and illustrated without departing from its spirit or scope. 

1. A composite mold for molding a part having a textured surface, the composite mold comprising: a mold base forming the base of a composite mold and having a mold base surface; a spray formed thin layer including a first surface having one or more fine features and a second surface opposing the first surface, the second surface being coupled to the mold base to form the composite mold having the first surface as the molding surface, and the composite mold being capable of forming a molded part having a textured surface including surface features representing a reciprocal facsimile of the one or more fine features.
 2. The composite mold of claim 1, wherein the one or more fine features includes one or more features selected from the group consisting of: one or more grooves and one or more projections.
 3. The composite mold of claim 2, wherein at least one of the one or more grooves includes an arcuate portion or a linear portion.
 4. The composite mold of claim 2, wherein at least one of the one or more projections includes an arcuate portion or a linear portion.
 5. The composite mold of claim 1, wherein the spray formed thin layer is formed of a metal or metal alloy.
 6. The composite mold of claim 1, wherein the spray formed thin layer has a nominal thickness of 2 to 20 mils.
 7. The composite mold of claim 1, further comprising an adhesive for adhering the second surface to the mold base.
 8. The composite mold of claim 1, wherein the mold base is formed from a metal or metal alloy.
 9. The composite mold of claim 1, wherein the molded part is a part for the interior of a vehicle.
 10. A spray formed thin layer comprising: a first surface and a second surface opposing the first surface; a layer portion extending between the first and second surfaces, the first surface having one or more fine features.
 11. The spray formed thin layer of claim 10, wherein the one or more fine features includes one or more features selected from the group consisting of: one or more grooves and one or more projections.
 12. The spray formed thin layer of claim 11, wherein at least one of the one or more grooves includes an arcuate portion or a linear portion.
 13. The spray formed thin layer of claim 11, wherein at least one of the one or more projections includes an arcuate portion or a linear portion.
 14. The spray formed thin layer of claim 11, wherein the spray formed thin layer is formed of a metal or metal alloy.
 15. The spray formed thin layer of claim 11, wherein the spray formed thin layer is formed of a metal or metal alloy having a metal oxide content of less than or equal to 5%.
 16. The spray formed thin layer of claim 11, wherein the one or more fine features is an intricate array of channels.
 17. The spray formed thin layer of claim 11, wherein the layer portion has a nominal thickness of 2 to 20 mils.
 18. A method for forming a spray formed thin layer, the method comprising: providing a spray target having a spray surface; depositing a metal spray onto the spray target surface to form a deposit layer having an interfacing surface; and releasing the deposit layer from the spray target surface.
 19. The method of claim 18, wherein the providing step includes forming one or more fine features on the interfacing surface.
 20. The method of claim 18, wherein the depositing step includes forming one or more fine features on the interfacing surface. 